Mask for crystallizing silicon, apparatus having the mask and method of crystallizing with the mask

ABSTRACT

A mask for crystallizing silicon includes a first, a second, and a third pattern part arranged in a longitudinal direction, each of the first, second, and third pattern parts including a plurality of unit blocks for transmitting and blocking a portion of light. At least two of the first, second and third pattern parts have a corresponding pattern to each other. Advantageously, scans using the aforementioned mask effectively remove a boundary on the silicon formed by the difference in the amount of laser beam irradiation received by the silicon, thereby improving electronic characteristics of the silicon.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Korean Patent Application No.2005-0124634 filed on Dec. 16, 2005, the contents of which are hereinincorporated by reference in their entirety.

BACKGROUND

1. Field of the Invention

The present invention relates to a mask for crystallizing silicon and anapparatus having the mask. More particularly, the present inventionrelates to a mask for crystallizing silicon capable of improvingelectric characteristics of silicon and an apparatus having the mask.

2. Description of the Related Art

In general, an amorphous silicon thin film transistor (a-Si TFT) hasbeen used as a switching element in a liquid crystal display apparatus.Recently, a poly crystalline silicon thin film transistor (poly-Si TFT)having a higher operation speed has been used for the liquid crystaldisplay apparatus to display an image of a high display quality.Particularly, in an organic light emitting display (OLED) device havingan organic light emitting diode that is driven by a current, the poly-SiTFT has been widely used for a switching element, a driving element,etc.

The method of forming a poly crystalline silicon thin film of thepoly-Si TFT has included directly forming the poly-Si TFT on asubstrate, and forming an amorphous silicon thin film on the substrateand then heating the amorphous silicon thin film to form the polycrystalline silicon thin film, etc. A laser has been generally used forthe heating step.

According to the heating method using the laser, a laser beam generatedfrom the laser melts the amorphous silicon thin film on the substrate.The melted silicon is crystallized into a plurality of grains that growsaround a plurality of nuclei to form the poly silicon thin film havinggood crystalline characteristics. Therefore, the amorphous silicon thinfilm is changed to the poly crystalline silicon thin film that has ahigher electric conductivity than the amorphous silicon thin film.

The laser beam generated from the laser may be directly irradiated ontothe substrate in one example, or it may be irradiated through a mask inanother example. The mask includes a plurality of slits for transmittingthe laser beam.

The mask having a small size is transported on the substrate inhorizontal and longitudinal directions of the substrate to irradiate thelaser beam to an entire surface of the substrate. That is, the mask istransported on the substrate in the longitudinal and horizontaldirections at a predetermined distance, and the laser beam is thenirradiated onto the substrate so that substantially the entire amorphoussilicon thin film of the substrate is changed to a poly crystallinesilicon thin film.

However, when the mask is transported to the longitudinal and horizontaldirections, a scanning of the laser beam is overlapped with adjacentscanning of the laser beam. That is, a portion of the silicon thin filmon the substrate is repeatedly exposed to the laser beam on thesubstrate. The substrate is divided into a first part where the laserbeam is irradiated once, and a second part where the laser beam isrepeatedly irradiated. The first part and the second part have differentelectronic characteristics.

Moreover, when dividing the first part and the second part according tothe amount of the irradiation of the laser beam, a structure of the polysilicon thin film on or near a boundary between the first and secondparts on the substrate is different from that of a remaining portion ofthe poly silicon thin film. The boundary deteriorates the electricalcharacteristics of the poly crystalline silicon thin film, such aselectric conductivity.

SUMMARY

The present invention provides an advantageous mask for crystallizingsilicon capable of decreasing the disadvantageous effects of a boundaryon a poly silicon thin film formed from overlapping irradiation of alaser beam, thereby improving electrical characteristics of the silicon.The present invention also provides an apparatus for crystallizingsilicon having the above-mentioned mask.

A mask for crystallizing silicon in accordance with an aspect of thepresent invention includes a first pattern part, a second pattern partand a third pattern part arranged in a longitudinal direction. At leasttwo of the first, second and third pattern parts have a correspondingpattern to each other.

A plurality of unit blocks is formed on each of the first, second andthird pattern parts. The unit blocks transmit a portion of light, andblock a portion of the light to crystallize the silicon. The unit blocksmay include a plurality of transmission blocks that transmit a portionof the light, and a plurality of blocking blocks that block a portion ofthe light. Each of the first, second and third pattern parts may includea plurality of sub pattern parts.

A mask for crystallizing silicon in accordance with another aspect ofthe present invention includes a first pattern part and a second patternpart formed in a longitudinal direction of the mask.

A plurality of unit blocks transmitting a portion of a light andblocking a remaining portion of the light is formed in each of the firstand second pattern parts. The first pattern part has an opposite patternto the second pattern part.

An apparatus for crystallizing silicon in accordance with another aspectof the present invention includes a stage, a laser and a mask. Theapparatus for crystallizing silicon may further include a transportationunit and an optical unit.

The stage supports a substrate having amorphous silicon. The laser isformed over the substrate. The laser irradiates a laser beam onto thesubstrate, and changes the amorphous silicon to poly crystallinesilicon. The mask is disposed between the substrate and the laser. Themask transmits a portion of the laser beam irradiated onto thesubstrate, and blocks a remaining portion of the laser beam. The maskincludes a first pattern part, a second pattern part and a third patternpart arranged in a longitudinal direction of the substrate. At least twoof the first, second and third pattern parts have a correspondingpattern to each other. Each of the first, second and third pattern partsincludes a plurality of unit blocks transmitting a portion of the laserbeam and blocking a portion of the laser beam to crystallize theamorphous silicon. The unit blocks are in each of the first, second andthird pattern parts.

The transportation unit transports the stage so that the laser beam isirradiated onto substantially the entire substrate. The optical unit isattached to the laser to change optical characteristics of the laserbeam.

According to the present invention, at least two of the first, secondand third pattern parts include corresponding patterns such that thecorresponding patterns of the mask are partially overlapped duringadjacent scanning processes thereby overall uniformly irradiatingunderlying silicon although scanned more than one time. Therefore, thelaser beam is uniformly irradiated onto the amorphous silicon thin filmso that the boundary between the adjacent scanning processes may haveuniform structure, thereby improving electric characteristics of thesilicon formed on the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other advantages of the present invention will becomereadily apparent by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings, wherein:

FIG. 1 is a cross-sectional view illustrating an apparatus forcrystallizing silicon in accordance with one embodiment of the presentinvention;

FIG. 2 is a plan view illustrating a process of crystallizing silicon onsubstantially the entire surface of a substrate by the apparatus of FIG.1;

FIGS. 3A to 3C are enlarged plan views illustrating a mask of FIG. 1 forcrystallizing silicon;

FIG. 4 is a plan view illustrating longitudinal and horizontal transportof the mask of FIG. 3A for crystallizing silicon;

FIGS. 5A to 5C are plan views illustrating a mask of an apparatus forcrystallizing silicon in accordance with another embodiment of thepresent invention;

FIG. 6 is a plan view illustrating longitudinal and horizontaltransportations of the mask of FIG. 5A;

FIGS. 7A to 7C are plan views illustrating a mask of an apparatus forcrystallizing silicon in accordance with another embodiment of thepresent invention; and

FIG. 8 is a plan view showing longitudinal and horizontal transport ofthe mask of FIG. 7A.

DESCRIPTION OF THE EMBODIMENTS

The invention is described more fully hereinafter with reference to theaccompanying drawings, in which embodiments of the invention are shown.This invention may, however, be embodied in many different forms andshould not be construed as limited to the embodiments set forth herein.Rather, these embodiments are provided so that this disclosure will bethorough, and will fully convey the scope of the invention to thoseskilled in the art. In the drawings, the size and relative sizes oflayers and regions may be exaggerated for clarity.

It will be understood that when an element or layer is referred to asbeing “on,” “connected to” or “coupled to” another element or layer, itcan be directly on, connected or coupled to the other element or layer,or intervening elements or layers may be present. In contrast, when anelement is referred to as being “directly on,” “directly connected to”or “directly coupled to” another element or layer, there are nointervening elements or layers present. Like numbers refer to likeelements throughout. As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, third etc.may be used herein to describe various elements, components, regions,layers and/or sections, these elements, components, regions, layersand/or sections should not be limited by these terms. These terms areonly used to distinguish one element, component, region, layer orsection from another region, layer or section. Thus, a first element,component, region, layer or section discussed below could be termed asecond element, component, region, layer or section without departingfrom the teachings of the present invention.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a,” “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Embodiments of the invention are described herein with reference tocross-section illustrations that are schematic illustrations ofidealized embodiments (and intermediate structures) of the invention. Assuch, variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, embodiments of the invention should not be construed aslimited to the particular shapes of regions illustrated herein but areto include deviations in shapes that result, for example, frommanufacturing. For example, an implanted region illustrated as arectangle will, typically, have rounded or curved features and/or agradient of implant concentration at its edges rather than a binarychange from implanted to non-implanted region. Likewise, a buried regionformed by implantation may result in some implantation in the regionbetween the buried region and the surface through which the implantationtakes place. Thus, the regions illustrated in the figures are schematicin nature and their shapes are not intended to illustrate the actualshape of a region of a device and are not intended to limit the scope ofthe invention.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

Hereinafter, the present invention will be explained in detail withreference to the accompanying drawings.

FIG. 1 is a cross-sectional view illustrating an apparatus 1000 forcrystallizing silicon in accordance with one embodiment of the presentinvention. FIG. 2 is plan view illustrating a process of crystallizingsilicon on substantially the entire surface of a substrate by theapparatus 1000 of FIG. 1.

Referring to FIG. 1, the apparatus 1000 for crystallizing siliconincludes a laser 100, an optical unit 200, a stage 300, a mask 400 forcrystallizing silicon and a transportation unit.

In one example, the laser 100 continuously generates a laser beam.Alternatively, the laser 100 may intermittently generate the laser beam.The laser 100 may include an excimer laser. The excimer laser generatesa laser beam of short wavelength, high power and high efficiency. Awavelength of the laser beam generated by the excimer laser, forexample, may be between about 200 nm and about 400 nm, and preferablymay be between about 250 nm and about 308 nm. A frequency of the laserbeam, for example, may be between about 300 Hz and about 6000 Hz, andpreferably may be between about 4000 Hz and about 6000 Hz.

The optical unit 200 is attached to an entrance of the laser 100generating the laser beam. The optical unit 200 receives the laser beamthat is from the laser 100, and changes optical characteristics of thelaser beam to emit the laser beam outside of the optical unit 200. Forexample, the optical unit 200 changes a cross-sectional length or across-sectional width of the laser beam. Alternatively, the optical unit200 may change an intensity of the laser beam.

The stage 300 is disposed under the laser 100, and supports a substrate10 having amorphous silicon (a-Si). The amorphous silicon (a-Si) isformed as a thin film shape on the substrate 10.

The mask 400 for crystallizing silicon is disposed between the substrate10 and the laser 100, and transmits a portion of the laser beam andblocks a portion of the laser beam that is irradiated onto the substrate10. The laser beam is irradiated onto the amorphous silicon (a-Si)formed on the substrate 10, and changes the amorphous silicon (a-Si) topoly crystalline silicon (poly-Si). The mask 400 for crystallizingsilicon will be described in detail with reference to followingdrawings.

A transportation unit transports the stage 300 longitudinally andhorizontally so that the laser beam is irradiated onto substantially theentire surface of the substrate 10. The mask 400 for crystallizingsilicon is transported longitudinally and horizontally relative to thesubstrate 10 based on the transportation of the stage 300. Therefore,the laser beam is irradiated onto substantially the entire surface ofthe substrate 10 through the mask 400.

Referring to FIG. 2, the mask 400 for crystallizing silicon isrepeatedly transported between left and right end portions of thesubstrate 10. Particularly, the mask 400 for crystallizing silicon istransported from the left end portion to the right end portion of thesubstrate 10 at a first interval IT1 through a first scan. In the firstscan, the laser beam is intermittently irradiated onto the substrate 10through the mask 400 for crystallizing silicon, and the laser beam isalso transported from the left end portion to the right end portion ofthe substrate 10 at the first interval IT1. That is, the stage 300 isintermittently transported from right to left at the first interval IT1so that the mask 400 and the laser beam are intermittently transportedfrom the left portion to the right portion of the substrate 10 at thefirst interval IT1. The first interval IT1 at which the mask 400 forcrystallizing silicon is transported may be smaller than a width of themask 400 for crystallizing the silicon.

After the first scan is completed, the mask 400 for crystallizingsilicon is shifted at second intervals IT2 in a longitudinal directionthat is substantially perpendicular to a scanning direction of the firstscan. The second interval IT2 at which the mask 400 for crystallizingsilicon is transported, may be smaller than a length of the mask 400 forcrystallizing silicon.

The mask 400 is transported from the right end portion to the left endportion of the substrate 10 at the first interval IT1 through a secondscan. In the second scan, the laser beam is intermittently irradiatedonto the substrate 10 through the mask 400 for crystallizing silicon,and the laser beam is also transported from the right end portion to theleft end portion of the substrate 10 at the first interval IT1. That is,the stage 300 is intermittently transported from left to right at thefirst interval IT1 so that the mask 400 and the laser beam areintermittently transported from the right portion to the left portion ofthe substrate 10 at the first interval IT1. After the second scan iscompleted, the mask 400 for crystallizing silicon is shifted at thesecond interval IT2 in the longitudinal direction substantiallyperpendicular to a scanning direction of the second scan. The secondscan has substantially the same scanning direction as the first scan.

In the same manner as above, the mask 400 for crystallizing silicon istransported between the right end portion and the left end portion Ntimes, thereby completing N scans. The laser beam is irradiated ontosubstantially the entire surface of the substrate through the mask 400for crystallizing silicon using the N scans. Therefore, substantiallythe entire amorphous silicon (a-Si) is changed to poly crystallinesilicon (poly-Si).

FIGS. 3A to 3C are enlarged plan views illustrating a mask of FIG. 1 forcrystallizing silicon. FIG. 4 is a plan view illustrating longitudinaland horizontal transport of the mask of FIG. 3A for crystallizingsilicon.

Referring to FIGS. 3A to 3C and 4, the mask 400 includes a first patternpart 1AE, a second pattern part 2AE and a third pattern part 3AEarranged in a longitudinal direction, in sequence. In one example, mask400 has a length ‘a’ of about 15 mm, and a width ‘b’ of about 2 mm.

The unit blocks 410 are formed in the first, second and third patternparts 1AE, 2AE and 3AE. The unit blocks transmit a portion of the laserbeam and block a portion of the laser beam. For example, the mask 400includes blocks of 15 rows and 6 columns.

The unit block 410 includes a transmission block 412 (shown by a clearblock) that transmits a portion of the laser beam, and a blocking block414 (shown by a hashed block) that blocks a portion of the laser beam.The transmission block 412 includes a plurality of slits 412 a thattransmits a portion of the laser beam. The slits 412 a of thetransmission block 412, for example, include a substantially rectangularform, and are arranged in a substantially parallel arrangement in thelongitudinal direction.

In one example, a pattern of the transmission and blocking blocks 412,414 of the first pattern part 1AE is substantially opposite to a patternof the transmission and blocking blocks 412, 414 of the third patternpart 3AE. The second pattern part 2AE includes only rows and columns oftransmission blocks 412 forming a whole transmission part W.

An arrangement of the transmission blocks 412 in the first pattern part1AE is substantially opposite to an arrangement of the transmissionblocks 412 in the third pattern part 3AE so that the patterns of thefirst pattern part 1AE have a substantially opposite shape to the thirdpattern part 3AE. In particular, the blocking blocks 414 of the thirdpattern part 3AE correspond to the transmission blocks 412 of the firstpattern part 1AE. The transmission blocks 412 of the third pattern part3AE correspond to the blocking blocks 414 of the first pattern part 1AE.

For example, the first pattern part 1AE may be an odd row transmissionpart O. In the odd row transmission part O, the transmission blocks 412are disposed in odd-numbered rows, and the blocking blocks 414 aredisposed in even-numbered rows. In addition, the third pattern part 3AEmay be an even row transmission part E. In the even row transmissionpart E, the transmission blocks 412 are disposed in even-numbered rows,and the blocking blocks 414 are disposed in odd-numbered rows.Alternatively, the first pattern part 1AE may be the even rowtransmission part E, and the third pattern part 3AE may be the odd roetransmission part O.

Alternatively, the first pattern 1AE may be a progressively increasingtransmission part. In the progressively increasing transmission part,the number of the transmission blocks 412 increases gradually in alongitudinal direction from an upper side toward a lower side of theprogressively increasing transmission part. In addition, the thirdpattern part 3AE may be a progressively decreasing transmission part. Inthe progressively decreasing transmission part, the number of thetransmission blocks 412 decreases gradually in a longitudinal directionfrom an upper side toward a lower side of the progressively decreasingtransmission part. Alternatively, the first pattern 1AE may be theprogressively decreasing transmission part, and the third pattern 3AEmay be the progressive increasing transmission part.

For example, in FIGS. 3A to 3C and 4, the first pattern part 1AE is theodd row transmission part O, and the third pattern part 3AE is the evenrow transmission part E. Referring to FIG. 4, the mask 400 forcrystallizing silicon has the odd row transmission part, the wholetransmission part, and the even row transmission part that are arranged,in sequence. The mask for crystallizing silicon is transported from theleft end portion to the right end portion of the substrate at firstintervals IT1 in the horizontal direction that is substantiallyperpendicular to the longitudinal direction, thereby performing thefirst scan.

After the first scan is completed, the mask 400 for crystallizingsilicon is shifted in the longitudinal direction by a distance m. Thedistance m may be the second interval IT2 (shown in FIG. 2) in oneexample. The distance m may be about two thirds of the length of themask 400 in one example, and in a further example, the distance m isabout 10 mm.

After the shift of the mask 400 along the longitudinal direction of themask 400, the mask 400 is transported from the left end portion to theright end portion of the substrate at first intervals IT1 in thehorizontal direction that is substantially perpendicular to thelongitudinal direction, thereby performing the second scan.

In the second scan, the third pattern part 3AE of the first scan isoverlapped with the first pattern part 1AE of the second scan (i.e., thefirst pattern part 1AE overlaps an area of the silicon previouslyscanned by the third pattern part 3AE). The third pattern part 3AE ofthe first scan is the even row transmission part E, and the firstpattern 1AE of the second scan is the odd row transmission part O, sothat the laser beam is uniformly irradiated onto silicon under anoverlapped portion of pattern parts between the first and second scansas the overlapped portion provides overall uniform irradiation onto thesilicon during the two scans, although the overlapped portion is scannedtwice by the first and second scans. During the first scan, a portion ofthe underlying silicon is irradiated, and during a subsequent scan, aremaining portion of the underlying silicon is irradiated to provideuniform irradiation over the entire surface of the underlying silicon.In other words, the mask of the present invention allows for anoverlapped portion of pattern parts between two or more scans touniformly irradiate over the surface of underlying silicon by usingcorrelated transmission and blocking patterns for selective irradiation,thereby substantially preventing the formation of boundaries caused bynon-uniform irradiation over the surface of the silicon.

In the same manner as above, the mask 400 for crystallizing silicon istransported between the left end portion and the right end portion ofthe substrate so that substantially the entire amorphous silicon (a-Si)formed on the substrate 10 is changed to poly crystalline silicon(poly-Si).

In accordance with the apparatus 1000 and the mask 400 for crystallizingsilicon shown in FIGS. 1 to 4, the third pattern part 3AE has asubstantially opposite shape to the first pattern part 1AE. The thirdpattern part 3AE and the first pattern part 1AE are partially overlappedduring the adjacent scans that transport mask 400 between the left endportion and the right end portion of the substrate 10. Although thelaser beam is scanned two times on the overlapped portion between theadjacent scans, the laser beam is uniformly irradiated onto thesubstrate 10 effectively one time through the first and third patternparts 1AE and 3AE that have opposite patterns. Thereby, the poly siliconthin film on a boundary between the overlapped portion and a centralportion of each of the scans has substantially the same structure as thepolysilicon thin film on the overlapped portion and the central portionof each of the scans, thereby improving the electrical characteristicsof the poly crystalline silicon (poly-Si) formed on the substrate 10.

As noted above in one example, the mask 400 for crystallizing siliconmay include blocks of fifteen rows and six columns. Alternatively, themask 400 for crystallizing silicon may include blocks of fifteen rowsand eighteen columns.

When the mask 400 for crystallizing silicon includes fifteen rows andeighteen columns, the mask 400 may be divided into six rows, andincludes the first, second and third sub masks (not shown). The first,second and third sub masks have corresponding patterns to each otherwith respect to a central line of the mask 400 for crystallizingsilicon.

The transmission blocks 412 transmitting the laser beam may include anupper transmission block and a lower transmission block. Slits of theupper transmission block and slits of the lower transmission block aredisposed in different parts in the upper and lower transmission blocks.In order to completely change the amorphous silicon (a-Si) correspondingto each of the unit blocks on the substrate 10, the laser beam may beirradiated twice onto the unit block through the upper transmissionblock and the lower transmission block. That is, the upper transmissionblock has a substantially opposite shape to the lower transmissionblock.

For example, when the mask includes the first, second and third submasks and one unit block 410 of the first sub mask is the uppertransmission block, the unit block 410 of the second sub maskcorresponding to the upper transmission block of the first sub mask isone of the lower transmission block and the blocking block 414. Inaddition, the unit block 410 of the third sub mask corresponding to theupper transmission block of the first sub mask is another of the lowertransmission block and the blocking block 414.

The mask 400 for crystallizing silicon having the first, second andthird sub masks, is transported repeatedly at a distance that issubstantially the same as the width of each of the first, second andthird sub masks. The laser beam is then irradiated onto the substrate 10so that the amorphous silicon (a-Si) corresponding to each of the unitblocks 410 is changed to the poly crystalline silicon.

The apparatus for crystallizing silicon of FIGS. 5A to 5C and 6 issubstantially the same as in FIGS. 1 to 4 except for the mask forcrystallizing silicon. Thus, the same reference numerals will be used torefer to the same or like parts as those described in FIGS. 1 to 4 andfurther explanation concerning the above elements will be omitted.

FIGS. 5A to 5C are plan views illustrating a mask of an apparatus forcrystallizing silicon in accordance with another embodiment of thepresent invention. FIG. 6 is a plan view illustrating longitudinal andhorizontal transport of the mask of FIG. 5A.

Referring to FIG. 5, the mask 500 for crystallizing silicon includes afirst pattern part 1AE, a second pattern part 2AE and a third patternpart 3AE. The first, second and third pattern parts 1AE, 2AE and 3AE maybe aligned in a longitudinal direction of the mask 500 for crystallizingsilicon. Each of the first, second and third pattern parts 1AE, 2AE and3AE includes a plurality of sub pattern parts. For example, each of thefirst, second and third pattern parts 1AE, 2AE and 3AE include five subpattern parts. In a further example, a length ‘a’ of the mask 500 forcrystallizing the silicon may be about 25 mm, and a width ‘b’ of themask 500 for crystallizing the silicon may be about 1.2 mm.

A plurality of unit blocks 510 transmits a portion of a laser beam, andblocks a remaining portion of the laser beam. The unit blocks 510 areformed in each sub pattern part of the first, second and third patternparts 1AE, 2AE and 3AE. The unit blocks 510 include a transmission block512 that transmits a portion of the laser beam, and a blocking block 514that blocks a portion of the laser beam.

A pattern of the sub pattern parts of the first pattern part 1AE has asubstantially opposite shape to a pattern of the sub pattern parts ofthe third pattern part 3AE. The sub pattern parts of the second patternpart 2AE include a whole transmission part W. The first pattern part 1AEand the third pattern part 3AE may have a substantially symmetricstructure with respect to the second pattern part 2AE.

Particularly, the sub pattern parts in the first pattern part 1AE mayinclude an odd row transmission part O, an even row transmission part E,a progressively increasing transmission part I, a progressivelydecreasing transmission part D, the whole transmission part W, and awhole blocking part (not shown). The sub pattern parts in the thirdpattern part 3AE include the opposite configuration of the sub patternparts of the first pattern part 1AE.

In the odd row transmission part O, the transmission blocks 512 aredisposed in odd-numbered rows, and the blocking blocks 514 are disposedin even-numbered rows. In the even row transmission part E, thetransmission blocks 512 are disposed in even-numbered rows and theblocking blocks 514 are disposed in odd-numbered rows.

In the progressively increasing transmission part I, the number of thetransmission blocks 512 increases gradually in the longitudinaldirection from an upper side toward a lower side of the progressivelyincreasing transmission part. In the progressively decreasingtransmission part D, the number of the transmission blocks 512 decreasesgradually in the longitudinal direction from an upper side toward alower side of the progressively decreasing transmission part.

Entire columns and rows of the whole transmission part W include thetransmission blocks 512, and the entire whole blocking part (not shown)includes the blocking blocks 514.

Particularly, the sub pattern parts in the first pattern part 1AE havethe even row transmission part E, the progressively decreasingtransmission part D, the odd row transmission part O, the progressivelyincreasing transmission part I, and the even row transmission part Ethat are arranged, in sequence. The sub pattern parts in the thirdpattern part 3AE have an opposite arrangement to the sub pattern partsin the first pattern part 1AE, so that the sub pattern parts in thethird pattern part 3AE have the odd row transmission part O, theprogressively increasing transmission part I, the even row transmissionpart E, the progressively decreasing transmission part D, and the oddrow transmission part O that are arranged in sequence.

The mask 500 for crystallizing the silicon has the arrangement shown inFIG. 5A. Alternatively, the mask 500 for crystallizing silicon may havevarious arrangements, including in one example, mirror opposite subpattern parts in the first pattern part 1AE and the third pattern part3AE.

Referring to FIG. 6, the mask 500 for crystallizing the silicon istransported from a left end portion to a right end portion of thesubstrate at a first interval IT1 in a direction substantiallyperpendicular to the longitudinal direction of the mask 500 through afirst scan. The mask 500 is shifted in the longitudinal direction at adistance m in one example. The distance m of the mask 500 may be abouttwo thirds of a longitudinal length of the mask 500 in one example.

After the shift of the mask 500 along the longitudinal direction of themask 500, the mask 500 is transported from the right end portion to theleft end portion of the substrate at a second interval IT2 in adirection substantially perpendicular to the longitudinal direction,thereby performing the second scan.

In the second scan, the third pattern part 3AE of the first scan isoverlapped with the first pattern part 1AE of the second scan. A patternarrangement of the third pattern part 3AE of the first scan is oppositeto a pattern arrangement of the first pattern part 1AE of the secondscan, so that the laser beam is uniformly irradiated onto silicon underan overlapped portion between the first and second scans effectively onetime, although the overlapped portion is scanned twice by the first andsecond scans.

In the same manner as above, the mask 500 for crystallizing silicon istransported between the left end portion and the right end portion ofthe substrate so that substantially the entire amorphous silicon (a-Si)formed on the substrate 10 is changed into poly crystalline silicon(poly-Si).

Hereinafter, the apparatus of FIGS. 5A to 5C and 6 will be described incomparison to the apparatus in FIGS. 1 to 4.

In FIGS. 1 to 4, when a length of a mask 400 for crystallizing siliconis increased, a third pattern part 3AE has an opposite patternarrangement to a first pattern part 1AE. Each of the first, second andthird pattern parts 1AE, 2AE and 3AE has a simple pattern, so that thefirst, second and third pattern parts 1AE, 2AE and 3AE may be recognizedas different scans. That is, the pattern parts 1AE, 2AE and 3AE may berecognized as different scans, even though the third pattern part 3AEand the first pattern part 1AE are overlapped with each other and aretransported between the left end portion to the right end portion of thesubstrate. When the first, second and third pattern parts 1AE, 2AE and3AE are recognized as different scans, a boundary may be formed betweenthe first, second and third pattern parts 1AE, 2AE and 3AE.

In contrast, each the first, second and third pattern parts 1AE, 2AE and3AE of the mask 500 for crystallizing silicon is divided into aplurality of sub pattern parts. The divided sub pattern parts mayinclude the odd row transmission part O, the even row transmission partE, the progressively increasing transmission part I, the progressivelydecreasing transmission part D, the whole transmission part W, and thewhole blocking part (not shown).

When a pattern arrangement of the first pattern part 1AE is opposite toa pattern arrangement of the third pattern part 3AE, and the firstpattern part 1AE and the third pattern part 3AE have complex patterns,the first, second and third pattern parts 1AE, 2AE and 3AE may not berecognized as different scans, and the boundary may not be recognized.

The apparatus for crystallizing silicon of FIGS. 7A to 7C and 8 issubstantially the same as in FIGS. 1 to 4 except for the mask forcrystallizing silicon. Thus, the same reference numerals will be used torefer to the same or like parts as those described with respect to FIGS.1 to 4 and further explanation concerning the above elements will beomitted.

FIGS. 7A to 7C are plan views illustrating a mask of an apparatus forcrystallizing silicon in accordance with another embodiment of thepresent invention. FIG. 8 is a plan view illustrating longitudinal andhorizontal transport of the mask of FIG. 7A.

Referring to FIGS. 7A to 7C, the mask 600 for crystallizing siliconincludes a first pattern part 1AE, a second pattern part 2AE and a thirdpattern part 3AE. The first, second and third pattern parts 1AE, 2AE and3AE may be aligned in a longitudinal direction of the mask 600 forcrystallizing silicon. Each of the first, second and third pattern parts1AE, 2AE and 3AE includes a plurality of sub pattern parts. For example,each of the first, the second and the third pattern parts 1AE, 2AE and3AE may include five sub pattern parts. In the divided mask 600 forcrystallizing silicon, a length ‘a’ of the mask 600 for crystallizingsilicon may be about 25 mm, and a width ‘b’ of the mask 600 forcrystallizing silicon may be about 1.2 mm.

A plurality of unit blocks 610 that transmits a portion of a laser beamand blocks a portion of the laser beam, are formed in each sub patternpart of the first, second and third pattern parts 1AE, 2AE and 3AE. Theunit blocks 610 include a transmission block 612 that transmits aportion of the laser beam, and the blocking block 614 that blocks aportion of the laser beam.

The first, second and third pattern parts 1AE, 2AE and 3AE havecorresponding patterns to each other. Thus, the laser beam is uniformlyirradiated onto silicon under an overlapped portion between the firstand second scans effectively one time, although the overlapped portionis scanned twice by the first and second scans. The first, second andthird pattern parts 1AE, 2AE and 3AE may have a substantially symmetricstructure (e.g., a mirror image) with respect to a center of the subpattern parts of the second pattern part 2AE.

Particularly, when an n-th sub pattern part in one sub pattern part ofthe first, second and third pattern parts 1AE, 2AE and 3AE is the oddrow transmission part O, an n-th sub pattern part in another sub patternpart of the first, second and third pattern parts 1AE, 2AE and 3AE isone of the even row transmission part E and the whole blocking part (notshown), and an n-th sub pattern part in a remaining sub pattern part ofthe first, second and third pattern parts 1AE, 2AE and 3AE is the otherone of the even row transmission part E and the whole blocking part (notshown).

Additionally, when the n-th sub pattern part in one sub pattern part ofthe first, second and third pattern parts 1AE, 2AE and 3AE is theprogressively increasing transmission part I, the n-th sub pattern partin another sub pattern part of the first, second and third pattern parts1AE, 2AE and 3AE is one of the progressively decreasing transmissionpart D and the whole blocking part B, and the n-th sub pattern part in aremaining sub pattern part of the first, second and third pattern parts1AE, 2AE and 3AE is the other one of the progressively decreasingtransmission part D and the whole blocking part B.

Furthermore, when the n-th sub pattern part in one sub pattern part ofthe first, second and third pattern parts 1AE, 2AE and 3AE is the wholetransmission part W, the n-th sub pattern part in another sub patternpart of the first, second and third pattern parts 1AE, 2AE and 3AE isthe whole blocking part B, and the n-th sub pattern part in a remainingsub pattern part of the first, second and third pattern parts 1AE, 2AEand 3AE is the whole blocking part B.

Particularly, the sub pattern parts in the first pattern part 1AEinclude the odd row transmission part O, the progressively decreasingtransmission part D, the whole blocking part B, the whole blocking partB, and the even row transmission part E that are arranged, in sequence.The sub pattern parts in the second pattern part 2AE include the wholeblocking part B, the progressively increasing transmission part I, thewhole transmission part W, the progressively decreasing transmissionpart D, and the whole blocking part B that are arranged, in sequence.The sub pattern parts in the third pattern part 3AE include the even rowtransmission part E, the whole blocking part B, the whole blocking partB, the progressively increasing transmission part I, the odd rowtransmission part O that are arranged, in sequence.

The mask 600 for crystallizing the silicon has the arrangement shown inFIGS. 7A to 7C and 8. Alternatively, the mask 600 for crystallizingsilicon having the corresponding patterns to each other in the first,second and third pattern parts 1AE, 2AE and 3AE may have variousarrangements.

In FIGS. 7A to 7C and 8, the whole transmission part W and the wholeblocking part B may not be disposed next to each other, and the odd rowtransmission part O and the even row transmission part E may not bedisposed next to each other. In addition, the progressively increasingtransmission part I and the progressively decreasing transmission part Dmay not be disposed next to each other.

Referring to FIG. 8, the mask 600 for crystallizing silicon istransported from a left end portion to a right end portion of thesubstrate at a first interval IT1 in a direction substantially inperpendicular to the longitudinal direction of the mask 600 through afirst scan. After the first scan is completed, the mask 600 is shiftedin the longitudinal direction at a distance t1. The distance t1 may beabout one third of the length of the mask 600 in one example.

After the shift of the mask 600 along the longitudinal direction of themask 600 for crystallizing silicon, the mask 600 is transported from theright end portions to the left end portion of the substrate at a secondinterval IT2 in a direction substantially perpendicular to thelongitudinal direction, thereby performing the second scan. After thesecond scan is completed, the mask 600 for crystallizing the silicon isshifted along the longitudinal direction at a distance t2. The distancet2 may also be one third of the length of the mask 600 in one example.

Then, the mask for crystallizing silicon is transported from the leftend portion to the right end portion of the substrate at a thirdinterval IT3 in a direction substantially perpendicular to thelongitudinal direction, thereby performing the third scan.

In the third scan, the third pattern part 3AE of the first scan, thesecond pattern part 2AE of the second scan and the first pattern part1AE of the third scan are overlapped with each other.

The third pattern part 3AE of the first scan, the second pattern part2AE of the second scan and the third pattern part 3AE of the third scanhave the corresponding patterns to each other, so that the laser beam isuniformly irradiated onto silicon under an overlapped portion betweenthe first, second and third scans effectively one time, although theoverlapped portion is scanned three times by the first, second and thirdscans.

In the same manner as above, the mask 600 for crystallizing silicon istransported between the left end portion and the right end portion ofthe substrate so that substantially the entire amorphous silicon (a-Si)formed on the substrate 10 is changed into poly crystalline silicon(poly-Si).

Hereinafter, the apparatus of FIGS. 7A to 7C and 8 will be described incomparison with the apparatus in FIGS. 1 to 4.

The mask 600 for crystallizing silicon includes the first, second andthird pattern parts 1AE, 2AE and 3AE. Each of the first, second andthird pattern parts 1AE, 2AE and 3AE is divided into a plurality of subpattern parts.

In FIGS. 5A to 5C and 6, the first pattern part 1AE and the thirdpattern part 3AE have opposite patterns to each other, and an entiretyof the second pattern part 2AE includes the whole transmission part W.In contrast, in FIGS. 7A to 7C and 8, the first, second and thirdpattern parts 1AE, 2AE and 3AE have corresponding patterns to eachother.

That is, the entirety of the second pattern part 2AE of FIGS. 5A to 5Cand 6 is the whole transmission part W, but the second pattern part 2AEof FIGS. 7A to 7C and 8 has the corresponding pattern to the first andthird pattern parts 1AE and 3AE. Therefore, the laser beam is irradiatedonto silicon under an overlapped portion between the first, second andthird scans effectively one time, although the overlapped portion isscanned three times by the first, second and third scans.

Therefore, the first, second and third pattern parts 1AE, 2AE and 3AE ofFIGS. 7A to 7C and 8 have more complex patterns than the first, secondand third pattern parts 1AE, 2AE and 3AE of FIGS. 5A to 5C and 6, sothat the first, second and third pattern parts 1AE, 2AE and 3AE may notbe recognized as different scans, and a boundary formed by the first,second and third scans may not be recognized.

According to the present invention, the first pattern part has anopposite pattern to the third pattern part in one example. The firstpattern part and the third pattern part are overlapped with each other,and are transported between the left end portion and the right endportion of the substrate. Thus, the laser beam is irradiated ontosilicon under the overlapped portion between the first and second scanseffectively one time, although the overlapped portion is scanned twotimes by the first and second scans. Therefore, the boundary formed bythe difference in the amount of laser beam irradiation received on thesilicon may be reduced, and the electronic characteristics of the polycrystalline silicon (poly-Si) are improved.

Moreover, each of the first, second and third pattern parts includes aplurality of sub pattern parts. The first pattern part has oppositepattern arrangement to the third pattern part, or the first, second andthird pattern parts may have the corresponding patterns to each other.Thereby, the first, second and third pattern parts may not be recognizedas different scans so that the boundary formed by the scans may beremoved.

Although embodiments of the present invention have been described, it isunderstood that the present invention should not be limited to theseembodiments but various changes and modifications can be made by one ofordinary skill in the art within the spirit and scope of the presentinvention as hereinafter claimed.

1. A mask, comprising: a first pattern part, a second pattern part, anda third pattern part arranged in a longitudinal direction, each of thefirst, second, and third pattern parts including a plurality of unitblocks transmitting a portion of light and blocking a portion of thelight to selectively crystallize silicon, wherein the first pattern partand the third pattern part comprise a substantially symmetric structurewith respect to the second pattern part.
 2. The mask of claim 1, whereinthe unit blocks comprise a plurality of transmission blocks transmittinga portion of light, and a plurality of blocking blocks blocking aportion of the light.
 3. The mask of claim 2, wherein each of thetransmission blocks comprises a plurality of slits.
 4. The mask of claim2, wherein each of the first, second, and third pattern parts comprisesa plurality of sub pattern parts, and wherein each of the sub patternparts is one of: an odd row transmission sub pattern part includingtransmission blocks in odd-numbered rows and blocking blocks ineven-numbered rows; an even row transmission sub pattern part includingtransmission blocks in even-numbered rows and blocking blocks inodd-numbered rows; a transmission increasing sub pattern part, whereinthe number of transmission blocks is increased as a distance from a sideof the mask in the longitudinal direction is increased; a transmissiondecreasing sub pattern part, wherein the number of transmission blocksis decreased as a distance from a side of the mask in the longitudinaldirection is increased; a whole transmission sub pattern part includingonly transmission blocks; and a whole blocking sub pattern partincluding only blocking blocks.
 5. The mask of claim 4, wherein the subpattern parts of the first pattern part comprise a combination of atleast one of the odd row transmission sub pattern part, the even rowtransmission sub pattern part, the transmission increasing sub patternpart, the transmission decreasing sub pattern part, the wholetransmission sub pattern part, and the whole blocking sub pattern part,and wherein the sub pattern parts of the third pattern part comprise acombination of at least one of the even row transmission sub patternpart, the odd row transmission sub pattern part, the transmissiondecreasing sub pattern part, the transmission increasing part, the wholeblocking sub pattern part, and the whole transmission sub pattern part,wherein the combination of the sub pattern parts of the third patternpart is opposite to the combination of the sub pattern parts of thefirst pattern part.
 6. The mask of claim 4, wherein the first, second,and third pattern parts comprise a substantially symmetric structurewith respect to a center of the first, second, and third pattern partsin the longitudinal direction.
 7. The mask of claim 4, wherein an n-thsub pattern part of one of the first, second, and third pattern parts isan odd row transmission sub pattern part, and wherein an n-th subpattern part of another of the first, second, and third pattern parts isone of an even row transmission sub pattern part and a whole blockingsub pattern part, and wherein the n-th sub pattern part of a remainingof the first, second, and third pattern parts is a remainder of the evenrow transmission sub pattern part and the whole blocking sub patternpart.
 8. The mask of claim 4, wherein an n-th sub pattern part of one ofthe first, second, and third pattern parts is a transmission increasingsub pattern part, further wherein an n-th sub pattern part of another ofthe first, second and third pattern parts is one of the transmissiondecreasing sub pattern part and the whole blocking sub pattern part, andfurther wherein an n-th sub pattern part of a remaining of the first,second and third pattern parts is a remainder of the transmissiondecreasing sub pattern part and the whole blocking sub pattern part. 9.The mask of claim 4, when wherein an n-th sub pattern part of one of thefirst, second and third pattern parts is the whole transmission subpattern part, further wherein an n-th sub pattern part of another of thefirst, second and third pattern parts is the whole blocking sub patternpart, and further wherein an n-th sub pattern part of a remaining of thefirst, second and third pattern parts is the whole blocking sub patternpart.
 10. The mask of claim 4, wherein each of the first, second andthird pattern parts comprises five sub pattern parts, and wherein thesub pattern parts of the first pattern part includes the odd rowtransmission sub pattern part, the transmission decreasing sub patternpart, the whole blocking sub pattern part, the whole blocking subpattern part, and the even row transmission sub pattern part, insequence, and wherein the sub pattern parts of the second pattern partincludes the whole transmission sub pattern part, the transmissionincreasing sub pattern part, the whole transmission sub pattern part,the transmission decreasing sub pattern part, and the whole blocking subpattern part, in sequence, and wherein the sub pattern parts of thethird pattern part includes the even row transmission sub pattern part,the whole blocking sub pattern part, the whole blocking sub patternpart, the transmission increasing sub pattern part, and the odd rowtransmission sub pattern part, in sequence.
 11. A mask, comprising: afirst pattern part and a second pattern part formed in a longitudinaldirection, each of the first and second pattern parts including aplurality of unit blocks transmitting a portion of light and blocking aportion of the light to selectively crystallize silicon, the firstpattern part having an opposite pattern to the second pattern part suchthat silicon under an overlapped portion of the first pattern part andthe second pattern part is uniformly irradiated.
 12. The mask of claim11, wherein the first and second pattern parts comprise a substantiallysymmetric structure with respect to a center of the first and secondpattern parts in the longitudinal direction.
 13. The mask of claim 11,wherein the unit block comprises a transmission block transmitting aportion of light, and a blocking block blocking a remaining portion ofthe light.
 14. The mask of claim 11, wherein one of the first and secondpattern parts comprises a plurality of rows, the transmission blocksbeing on odd-numbered rows and the blocking blocks being oneven-numbered rows, and wherein another of the first and second patternparts comprises a plurality of rows, the blocking blocks being onodd-numbered rows and the transmission blocks being on even-numberedrows.
 15. The mask of claim 11, wherein the number of the transmissionblocks of one of the first and second pattern parts is increased as adistance from the second pattern part in the longitudinal direction isincreased, and wherein the number of the transmission blocks of anotherof the first and second pattern parts is decreased as a distance fromthe second pattern part in the longitudinal direction is increased. 16.The mask of claim 11, wherein each of the first and second pattern partscomprises a plurality of sub pattern parts, wherein each of the subpattern parts is one of: an odd row transmission sub pattern partincluding transmission blocks in odd-numbered rows and blocking blocksin even-numbered rows; an even row transmission sub pattern partincluding transmission blocks in even-numbered rows and blocking blocksin odd-numbered rows; a transmission increasing sub pattern part,wherein the number of the transmission blocks is increased as a distancefrom a side of the mask in the longitudinal direction is increased; atransmission decreasing sub pattern part, wherein the number of thetransmission blocks is decreased as a distance from a side of the maskin the longitudinal direction is increased; a whole transmission subpattern part only including transmission blocks; and a whole blockingsub pattern part only including blocking blocks.
 17. The mask of claim16, wherein the sub pattern parts of the first pattern part comprise acombination of at least one of the odd row transmission sub patternpart, the even row transmission sub pattern part, the transmissionincreasing sub pattern part, the transmission decreasing sub patternpart, the whole transmission sub pattern part, and the whole blockingsub pattern part, and wherein the sub pattern parts of the secondpattern part comprise a combination of at least one of the even rowtransmission sub pattern part, the odd row transmission sub patternpart, the transmission decreasing sub pattern part, the transmissionincreasing sub pattern part, the whole blocking sub pattern part, andthe whole transmission sub pattern part, wherein the combination of thesub pattern parts of the second pattern part is opposite to thecombination of the sub pattern parts of the first pattern part.
 18. Amask, comprising: a first pattern part, a second pattern part, and athird pattern part arranged in a longitudinal direction, each of thefirst, second, and third pattern parts including a plurality of unitblocks transmitting a portion of light and blocking a portion of thelight to selectively crystallize silicon, wherein the first pattern parthas a substantially opposite pattern to the third pattern part withrespect to the second pattern part.
 19. The mask of claim 18, whereinthe unit blocks comprise a plurality of transmission blocks transmittinga portion of light, and a plurality of blocking blocks blocking aportion of the light.
 20. The mask of claim 19, wherein each of thetransmission blocks comprises a plurality of slits.
 21. The mask ofclaim 18, wherein one of the first and third pattern parts comprises aplurality of rows, the transmission blocks being on odd-numbered rowsand the blocking blocks being on even-numbered rows, and further whereinthe other of the first and third pattern parts comprises a plurality ofrows, the blocking blocks being on odd-numbered rows and thetransmission blocks being on even-numbered rows.
 22. The mask of claim18, wherein the number of the transmission blocks of one of the firstand third pattern parts is increased, as a distance from the secondpattern part in the longitudinal direction is increased, and furtherwherein the number of the transmission blocks of the other of the firstand third pattern parts is decreased, as a distance from the secondpattern part in the longitudinal direction is increased.
 23. The mask ofclaim 18, wherein the second pattern part comprises a plurality of rowsonly including transmission blocks.